1. Field of the Invention
The present invention relates to a multi-spot call system, a sound volume adjustment device, a portable terminal device, and a sound volume adjustment method used therefor and a program thereof, and more particularly, to a sound volume adjustment method on a reception side in a multi-spot call system such as an inter-multi-spot conference device.
2. Description of the Related Art
In conventional terminal devices used in multi-spot call systems of this kind, even if a transmission terminal is changed to have the sound volume heavily varying with one who speaks, because of lack of an effective means for adjusting the volume appropriately, each end user needs to speak carefully.
Under these circumstances, proposed for conventional multi-spot call systems is a method, in a telephone set used by a plurality of persons mainly for domestic use, of extracting/identifying one who speaks and using information (sound volume information and speech speed information) set in advance at a table relevant to the speaker to change properties such as the sound volume and a speech speed of the telephone set (see e.g. Japanese Patent Laying-Open (Kokai) No. 2000-312247). With this method, such operation is not required of increasing the sound volume every time the old who are hard to hear a little sound and not good at minute operation answer the telephone.
Also proposed for conventional multi-spot call systems is a method of storing pre-set amplitude/attenuation rate of a voice signal in a voice management information storage means so as to be correlated with a calling party to adjust the sound volume at an information terminal such as a PC (personal computer). The method is characterized in that voice management information is set in advance in some manner or other and is exchanged between information terminals through a network (see e.g. Japanese Patent Laying-Open (Kokai) No. 2001-094604).
Conventional multi-spot call systems are further characterized in that in a voice input terminal connected to a multi-spot TV conference system, a voice adjustment means is provided at an input side to adjust a difference between appropriate sound volume of the other party's terminal which is set in advance and input sound volume of its own terminal and output the appropriate sound volume to a network (see e.g. Japanese Patent Laying-Open (Kokai) No. 09-149133).
With the above-described conventional multi-spot communication systems, however, in a case of using the technique disclosed in the above-described Patent Article 1, when a plurality of persons make a call simultaneously at multiple spots, it is impossible to make dynamic adjustment of the sound volume according to the volume of the other party's voice, surrounding noise and the like to hear with the constant sound volume.
In addition, with the conventional multi-spot communication systems, however, in a case of using the technique disclosed in the above-described Patent Article 2, when a plurality of persons make a call simultaneously at multiple spots similarly to the above-described case, it is impossible to make dynamic adjustment of the sound volume according to the volume of the other party's voice, surrounding noise and the like to hear with the constant sound volume.
Furthermore, with the conventional multi-spot communication systems, however, in a case of using the technique disclosed in the above-described Patent Article 3, while the technique is effective for a terminal of a TV conference system disposed fixedly at a specific position to be used under constant environments, it is impossible to make dynamic adjustment of the sound volume according to the volume of the other party's voice, surrounding noise and the like to hear with the constant sound volume.